He founded the business in 1964 with a single psychiatric hospital in Sydney. Today the company has more than 150 hospitals located across five countries – Australia, England, France, Indonesia and Malaysia. It employs more than 30,000 people and admits over 1.4 million patients each year.

Mr Ramsay sold his 30 per cent stake in Prime Media in February, severing his long-standing ties with the media sector and netting around $96 million.

The billionaire started Ramsay Health Care when he was just 28 years old. He grew up in Burradoo in the Southern Highlands and after completing his high school education at St Ignatius College Riverview, he initially attended Sydney University and studied law.

But after working with his property surveyor father on subdivisions, his focus shifted.

Mr Ramsay's first major property purchase was a guest house on Sydney's North Shore, which he then converted into a 16-bed private psychiatric hospital after consulting with by psychiatrist John Ellard.

He expanded the psychiatric hospital business before expanding into mainstream hospitals in 1978.

While the recent history of Ramsay has been a story of dramatic growth, the company's initial expansion was far less smooth.

The company went close to the fall not long after it floated in 1988, and Mr Ramsay took it private again in 1992 before it returned to the ASX five years later.

The ageing of Australia's population and a push by political parties of both persuasions to encourage consumers to take out private health insurance provided Ramsay Health with the momentum needed for growth, with chief executive Pat Grier transforming the company from a minnow into a major player.

The hospital group has been one of the best performers on the ASX, with its shares jumping more than four-fold in the last five years as it expanded to Europe and, more recently, Asia.

Mr Grier said in 2012 that Mr Ramsay had carefully constructed "the Ramsay way", a set of six cultural principles that emphasises integrity and people.

"Paul is a true gentleman. I would describe him as a friend. But we also understand the boundaries of our roles as CEO and chairman," Mr Grier said in an interview with The Australian Financial Review.

Mr Ramsay entered the media sector in 1983, buying a stake in Prime Media and leading its expansion into regional areas through the acqusition of a number of operators, including Riverina TV and stations in Tamworth and Orange.

The group, which was long affiliated with the Seven Network, made an ill-timed investment in an television group in Argentina in 1997 and in more recent years has struggled with the wider downturn in the media sector.

Upon selling his stake in Prime in February, Mr Ramsay thanked his "good friend" Kerry Stokes for his personal support.

Mr Ramsay maintained a low media profile and rarely gave interviews during his career.

However, he regularly made headlines as a longstanding supporter of the Liberal Party – he was the party's biggest donor in 2011-12, giving $605,000 in one year – and a key corporate supporter of former prime minister John Howard.

He was also a noted, if publicity shy philanthropist; in 2011 he made a splash when he gave the charitable foundation of US actor Kevin Spacey $300,000 at a charity dinner.

Outside of Ramsay Health and Prime Media, Mr Ramsay's private investment vehicle, Paul Ramsay Group, held a range of eclectic investments, including stakes in digital advertising group Adstream International; internet TV firm Visionbytes; a resort in the American South called Nottoway; a legal solution business called Law of the Jungle; a wheat trading group; and the Sydney FC soccer team.